辽河西部凹陷页岩油气富集主控因素

Main controlling factors analysis of shale oil and gas accumulation in west sag of Liaohe depression

研究发现,泥页岩的有机质含量、成熟度、有机质类型、孔缝特征及厚度等内部因素是其能否富集的关键条件。以沙河街组沙三下亚段(Es33)和沙四上亚段(Es41)为例,在页岩油气影响因素研究的基础上,运用多因素综合评价、部分因素重点分析的方法,分别揭示Es33及Es41页岩油气富集的主控因素。综合认为,Es33有效厚度大,有机质丰度中等,热演化程度适中,有机质类型多样,气测异常明显、含油气性好,页岩油气共生,主要受有机质丰度影响;同Es33相比,Es41具有较高的有机质丰度,但有机质类型与热演化程度匹配较差,未能达到页岩气富集的条件,主体发育页岩油。因此,明确页岩油气富集的主控因素,是寻找页岩油气赋存有利区域的前提,对辽河坳陷页岩油气的勘探开发具有现实意义。

Study found that the key conditions for enrichment in mud shale are the organic matter content,maturity,organic matter type,apertures characteristics and thickness.By taking Es33 and Es41 of Shahejie formation as the examples,based on the influencing factors research of shale oil and gas,by use of comprehensive evaluation on multiple factors and key analysis of some factors,the main controlling factors of shale hydrocarbon accumulation in Es33 and Es41 of Shahejie formation have been revealed.The results show Es33 is characterized by big effective thickness,moderate organic matter abundance,moderate degree of thermal evolution,various organic matter types,abnormal gas logging,good oil-bearing properties and shale gas-oil association.Es33 ismainly affected by organic matter abundance.Compared with Es33,Es41 is of high organic matter abundance.However,the matching between organic matter type and thermal evolution degree is poor,and it failed to meet the conditions for shale gas accumulation,only developed with shale oil.Therefore,the main controlling factors of shale hydrocarbon accumulation should be made clear first,which is the basis for looking for shale oil and gas occurrence and has practical significance for shale oil and gas exploration and development in Liaohe depression.